Signaling system for railway and like installations



arch 8, 1938. I NlCOLAs 2,110,166

- SIGNALING SYSTEM FOR RAILWAY AND LIKE INSTALLATIONS Filed Dec. 4, 19352 sheets-sheet 1 INVENTOR= PAUL NICOLAS ATToRN 5Y5 March s, 1938. P LAS2,110,166

SIGNALING SYSTEM FOR RAILWAY AND LIKE INSTALLATIONS Filed Dec. 4, 1935 2She'hs-Sheet 2 INV-ENTOR= 7 PAUL NICOLA6 A'ILTORNENS Patented Mar. 8,1938 UNITED STATES PATENT, OFFICE SIGNALING SYSTEM FOR RAILWAY AND LIKEINSTALLATIONS Paul Nicolas, Paris, France, assignor to Societe FrancaiseRadio Electrique, a corporation of France Application December 4, 1935,Serial No. 52,838

g In France December 6, 1934 g 11 Claims. (Cl. 246+63) The presentinvention relates to Signaling systravelling vehicle itself of signalindications tems' for railway and like installations and is which arenormally given by indicators arranged particularly applicable to therepetition of sigat intervals along the side of the track. nals in thecabs of locomotives, motor trains and To this end, there corresponds toeach signal other vehicles travelling on railway tracks of all indicatorlocated at the side of the track, a parkinds, whether electrified ornot, or insulated or ticular electrical combination which is transnot,and provided with either Wooden or metal lated on board the vehicle byan ordinary signal sleepers. (coloured lamp, bell, horn, or the like)according One object of the invention is to provide a sigto apre-arranged code. This signal is normally 0 naling system for railwayand like installations produced at the moment when the vehicle passes ofthe kind wherein the signals are given under the corresponding indicatorposition along the the control of an electrical system which protrack.It may, furthermore, be so arranged that vides for the co-operationbetween elements stathe signal given on the vehicle persists after thetionary along the side of the track and elements indicator position hasbeen passed and has to carried by the travelling vehicle, but which isof undergo a resetting operation carried out by the 15 improvedconstruction and operation over the driver of the vehicle. Theproduction of the systems hitherto proposed. signal and this resettingoperation may be regis- Another object of the invention is to providetered on a band of paper by any known process, an improved electricallyoperated signaling sysfor example, mechanical, in order to show that temfor railway and like installations involving the signal has beenproperly produced and has 20 the co-operation of stationary electricalelebeen properly noted. ments provided along the side of the track withThe electrical system operates by induction electrical elements carriedby the travelling vewithout mechanical contact between the movable hiclewhereby the operation of the system is obelements of the apparatus andthe stationary ele- 5 tained by means of electric currents ofaudioments. The stationary apparatus located along frequency and Withoutdepending upon sharp the side'of the track adjacent to the indicatorsresonance for the successful co-operation of the are composed entirelyof inert elements, all the electrical elements. I necessary sources ofcurrent being carried on the Another and more specific object of theinvehicle. In addition to these advantages which vention is to providean improved signaling sysare common to other known arrangements, the 30term for railway and like installations whereby a system according tothe invention has also the plurality of different signals may beselectively advantage that the determination of the differgiven on thetravelling vehicle by means of an ent signals is not dependent uponsharp resoelectrical system operating by electro-magnetic nancesnecessitating on the part of the source induction and which provides forthe co operaor sources of-alternating current used, great stationbetween elements stationary along the side bility of frequency. Finally,the system may be of the track and elements carried by the travelsoarranged that if the mechanism of the signal ling Vehicle but Withoutdepending po Sharp indicator ceases to function the indication givenresonance for the successful operation of the 00- on the vehicle isnecessarily that of a blocked 40 operating electrical elements. track. a4

A still further object of the invention is to The number of the separatesignals which it is provide an improved signaling system for railgenerally desired to repeat on the vehicle is three. way and likeinstallations which is adapted to However, with the arrangementaccording to the give signal indications on the travelling vehicleinvention hereinafter to be described there may by means of anelectrical system which provides easily be obtained four distinctindications. It 5 for the co-operation between stationary elements willalso be appreciated that there is nothing to provided along the side ofthe track and further prevent a generalization of the system so thatelements carried by the moving vehicle, in comit gives a larger numberof indications. bination with means for controlling the said sig- Theabove and further objects, advantages and nals in accordance with thecondition of a track features of the invention will be more clearly 50section ahead of the track section on which the understood from thedescription of a preferred travelling vehicle is moving. embodimentthereof, which is given hereinafter,

In carrying the invention into practice, the imbyway of example, withreference to the accompro-ved signaling system according to theinvenpanying drawings, in which:

tion provides preferably for the indication on the Figure l is a.general diagram of an installa- 5 tion on the moving vehicle and acircuit arranged at the side of the track,

Figure 2 is a modification of the circuit arranged at the side of thetrack according to Figure 1,

Figure 3 represents diagrams explaining the operationof the receiver onthe vehicle, Figure 4 shows in detail the diagram of the receiver on thevehicle, v

Figure 5 shows a further modification of the circuit arranged at theside of the track; and

Figure 6 shows the signal indicating circuits controlled by thereceiver.

With reference to Figure 1,.the signal indicating system comprises:

1. On the vehicle a. A generator of alternating current G usually ofsingle phase supplying a coil S termed the emitter coil. In series withG and S are arranged various electrical elements such as a condenser C,a rheostat Rh, an ammeter D, etc. in order to regulate and control theintensity of the current supplied by G and also to improve the powerfactor of the circuit.

A receiver R, which will be more fully described hereinafter, issupplied with current derived from G by means of an impedance Iconnected in series with G and S.

The frequency of the currentgiven by G will preferably be chosen of anaverage audiofrequency, for example, from 400 to 2,000 periods persecond. y

b. A coil F termed the receiving coil.

Under certain conditions, as will hereinafter be described, thereceiving coil F is influenced bythe coil S and becomes the seat of anelectromotive force. The arrangement is normally such that when S and Fare not coupled with other circuits, the electromotive force induced byS in F is small or nil.

The receiving coil F is connected to the receiver R as shown.

c. The receiver R which permits or roughly measuring in value andsignthe angle of phase between the electromotive force E induced in Fand the primary current Ip supplied by the generator G. The saidreceiver in turn operates relays which produce on the vehicle desiredoptical or audible signals.

I 2. On the ground along the track U Two fixed coils A and'B which, whenthe vehicle passes close to them, are coupled simultaneously with S andF. It is furthermore possible in many cases to replace the two coils Aand B by a single coil provided that this is of suflicient geometricaldimensions to be simultaneously .coupled with S and F. Finally, animpedance Z which is of different value according to the signal which itis desired to produce, is connected in parallel with A and B by themechanism of the track signal indicator.

The difierent coils S, F, A, B, may be provided or not with iron cores.

The operation of the system will readily be understood with reference toFigure 1.

When the unit carried by the vehicle and formed bythe emitter S and thereceiver coil F passes in the vicinity of A and B, an induced current isdeveloped in the circuit AB. Owing to the coupling existing between Band F, this induced current influences in its turn the coil F and thereceiver R. V

' This being the case, it will beunderstood that the phase angle betweenthe current flowing in the coil B and consequently between theelectromotive force induced in the coil F and the current flowing in S,the phase of which is taken as a basis, will depend substantially uponthe nature and the value of the impedance Z.

In a general manner, the coils A and B will be so constructed as topresent a considerable excess potential that is to say that the ratio oftheir selfinduction to their resistance will be such that at thefrequency of the current supplied by the generator G, the counterelectromotive force due to the self-induction of the coil is in absolutevalue several times greater than that due to the ohmic resistance.

Under these conditions, if no impedance Z is interposed, the current inthe coil B will be approximately in phase, for a suitable choice of thedirections of winding of the coils, with the primary current flowing inS.

If, on the contrary, there is interposed at Z a capacitative reactanceof small value compared with the inductive reactanceof the coils A andB, the current flowing in B will be approximately in phase oppositionwith the current in the emitter core S.

If there is interposed, on the other hand, at Z a resistance withoutappreciable self-induction or capacity and of small value as comparedwith the reactance of the coils A and B, the current in B will beapproximately lagging by a quarter of a 7 period behind the primarycurrent in the emitter coil S.

Finally, in order to cause the current in B to lead by a quarter of aperiod on the current in S, a slightly more complicated arrangement willbe employed which comprises the use of a third coil A1. The operation ofthis arrangement will readily be understood with reference to Figure 2.When it is desired to produce this combination, it will be arranged thatthe mechanism of the track signal indicator connects a small resistanceZ1 in parallel with A and places in circuit instead thereof a third coilA1 of mechanical and electrical dimensions similar to those of A andlocated in its immediate vicinity without being strongly coupledtherewith. A1 is Wound oppositely to A. In a modification of the samemethod, a similar operation could be carried out by inserting in thecircuit a coil Wound in an opposite direction in the place of coil Binfluencing F. As the circuit would otherwise be identical with that ofFig. 2, except for the opposite winding on the mentioned coil replacingcoil B, it is thought superfluous to illustrate such an obvious andslight variation. In either case, it is clear that if Z1 is a resistancehaving the same value as in the third case, the desired result will beattained.

The problem of the repetition of the signals on the vehicle thenresolves into the construction of a device adapted to measure the phaseangle existing between the primary current Ip of the emitter S and theelectromotive force collected in the coil F. Figure 3 shows the value ofthis phase angle in the different cases. In this figure, theelectromotive force E collected in F is represented by a vector (0E1,0E2, 0E3, 0E4, according to whether the first, second, third or fourthcase is being dealt with). This electromotive force is, of course, inadvance by a quarter of a period on I the current in the coil B.

This being the case, let there be drawn on Figure 3 two straight linesX1OX,Y1OY at an angle of 45with respect to 0E1, OEaOEs and DB4, and letit be imagined that a suitable electrical arrarigement actuated both bythe primary current Ip and the electromotive force OE, effects theexcitation of a relay R1 when OE is in the half plane below the straightline X1OX, but this relay is not excited when the vector OE is abovethis line. Let it be supposed also that a second relay R2 is excitedwhen the vector OH. is below the line YOY1 but that it is not excitedwhen the vector OE is above this line.

It will easily be seen that such relays can be connected to closecontacts controlling coloured lamps, bells, etc.

Given the above arrangement, it will now be seen that in the first caseabove mentioned, this will result in both R1 and R2 being de-energized.In the second case, R1 will be de-energized and. R2 will be energized.In the third case, both R1 and R2 will be energized, and in the fourthcase R1 will be energized and R2 will be de-energized.

Three of the above four cases may be made to correspond in any suitablemanner to the three signals which it is desired to reproduce.Preferably, the first mentioned case will be chosen to represent thesignal line blocked so that an accidental failure of current in therelays or a bad contact on the impedance Z will not give any otherindication.

' In Figure 41, there is illustrated by way of example, one manner ofconstructing the phase selecting device which permits of controlling therelays R1 and R2.

In the embodiment illustrated in Figure 4, the receiving coil F isshunted by a condenser C and a resistance 7*, this arrangement havingfor effect to select by the known method of resonance or tuning in thecircuit of F, the electromotive force E due to the coupling between Sand AB with respect to other accidental electromotive forces which maybe induced, and also to strengthen the current in the circuit of F. Theresistance 1' will nevertheless be given a value sufficiently small toavoid the resonance being too sharp and the possible Variations offrequency of the generator G having an influence on the operation of thearrangement. There is also connected to the terminals of the receivingcoil F the primary windings of a transformer T provided with twoidentical secondary windings. On the other hand, the primary current Ipof the emitter passes through the impedance I which is formed by aself-induction coil L, two resistances TI and T2 and a condenser C1 allconnected in series. The values of L, r1, T2, and C1, may be so chosenthat the sums of the potentials at the terminals of L and T1 on the onehand and of T2 and C1 on the other hand, are approximately equal anddisplaced in phase by -4=5 degrees with respect to the primary currentand therefore by 90 degrees between themselves. 1

These potentials supply respectively the primary windings of twotransformers T1 and T2, the secondaries of which are formed by two equalhalf windings which produce potentials of equal value but of oppositephase.

It will be seen from the connections of Figure 4 that each of the unitsformed by the secondary of one of the transformers T1 or T2 and one ofthe secondaries of the transformer T supplies a system of two rectifyingdevices V (thermionic valve or metallic rectifier). Each of thesesystems supplies a rectified current to the resistances W shunted by thecondensers K. If the different elements of the same name (W or K) aretruly equal to one another, it will easily be seen that no rectifiedcontinuous potential will appear between the points M1 and N1 for theelectromotive force of which the coil F is the seat will have its phaseshifted by +45 or -135 with respect to the primary current Ip, becauseat this moment the tensions introduced into the secondaries of thetransformer T1 by the secondary of the transformer T exactly compensatefor the tensions induced in the two halves of the secondary T1 by theprimary of this transformer. In the same way, as regards the differenceof potentials between the points M2 and N2, it will be zero when thephase between the electromotive force at F and the current I is -45 or+135", because an exact compensation takes place at this moment in thehalf-secondaries of the transformer T2. With suitably selecteddirections of winding primaries and secondaries of the transformers T,T1, T2, it can be arranged that there is obtained, for example, at M1and N1 a positive potential when in Figure 3 the vector OE is situatedin the half plane below the straight line XIOX (phase angle less than+45 or 135, and negative in the contrary case. Corresponding conditionscan also be obtained for M2N2 and Y1OY (the tension being positive forexample for a phase angle less than 45 or +135).

If the relays R1 and R2 were sufficiently sensitive, these could beconnected respectively between M1 and N1 and M2 and N2. In practice,however, it is found preferable to effect this connection through atriode amplifying valve or a gaseous discharge tube called anionized-gas grid-controlled relay and which is represented at Th on thedrawings. For example, the point M1 will be connected to the grid of theThyratron valve and N1 to its cathode. When an ionized-gasgrid-controlled relay is employed, it is preferable to connect the pointM1 to the grid through a fairly high resistance 13, the resistance ofthe grid-filament space of an ionized-gas grid-controlled relay beingadapted to be small when a considerable current flows between the anodeand cathode.

It will furthermore be noted that by giving sufficiently high values tothe capacities K, it is possible to obtain an operation of thearrangement such that these capacities are charged in a short time underthe action of the transformers T, T1, and T2 and rectifying elements V,while their discharge through the resistances W only takes place slowlyif the resistances W are of high value. This feature is of importancebecause when the vehicle is travelling at a high speed, the duration ofthe action between the coils A, B and S, F is small.

The arrangement is completed by the two relays R1 and R2 being excitedby the anode current of the ionized-gas grid-controlled relay valve Th,the plate circuit of which is supplied, for example, by the secondary ofa transformer T3, the primary winding of which is supplied by thegenerator G. The relays will then operate on failure of current when OEis in the half plane located above X1OX or YOY1.

Figure 6 represents the circuits controlled by the relays R1 and R2. Asshown, the relay R1 is provided with three armatures l, 2, 3. The roleof the armatures I and 2 will be explained more fully hereinafter whilethe armature 3 which oscillates between two pairs of contacts serves tocontrol the signaling circuits. The relay R2 is provided with fivearmatures 4, 5, 5, I, 8. The armature 4 is utilized in combination withthe armature 2 and itsoperation will be explained more fullyhereinafter. The armatures 5, 6, 1, 8

togetherwith the armature 3 control the signaling circuits, eacharmature closing a contact in the position of rest or of working. Thesignal indicating devices (lamps, horns or the like) are shown at 9, l0,H, and I2 and are supplied from a suitable source I3. It will be seenfrom the connections of the contacts of the two relays that when R1 andR2 are de-energized, the armatures 3 and 6 close the circuit of theindicating device i I which then operates. The simultaneous energizationof R1 and R2 effects the closing through the armatures 3 and of thecircuit of the indicating device l2. If the relay R1 is energized aloneand R2 is de-energized, the armatures 3 and 8 close the circuit of theindicating device 9. Finally, if R2 is energized and R1 is de-energized,the armatures 3 and I close the circuit of the indicating device In.Thus, a different indicating device is operated for each combination.

Naturally, in place of the arrangement described, any other means may beemployed for detecting the phase of the electromotive force in the coilF with respect to the current Ip. For example, a device similar to awatt meter or the like may be used.

An important application of the signaling arrangement, the principle ofwhich has been explained above, consists in combining the same with thesignaling arrangement forming the object of my oo-pending applicationNo. 15,962 of 12th April 1935, which device hasfor its object to revealthe presence in front of the vehicle equipped therewith, of anothervehicle the axles of which close the track circuit which is the seat ofthe currents induced by the emitter of the first vehicle.

The arrangement in said application consists in inducing the current inthe rails through a coil similar to S, collecting this current by meansof a coil similar to F and measuring by means of a receiver similar to Rthe phase displacement between the current supplied by a generatorsimilar to G and the current received, this phase displacement beingvariable with the distance from the short-circuit of the track.

The coils S and F must then be located on the vehicle in such manner asto be'coupled with the track circuit as strongly as possible. Thismodification can naturally only be employed if the track has insulatingsleepers and if the joints of the rails are sufficiently electricallyconductive.

In this case there will be used three ofthe four proposed positions ofthe vector OE for the repetition of the three signals line clear,"warning, line blocked, the fourth position corresponding to theoperation of the arrangement forming the object of my co-pendingapplication aforesaid. An interesting advantage of the above describedarrangement is that it is then possible to produce the signal line blockby using the mechanism of the track signal indicator to short circuitthe track, which has the advantage that the signal line blocked isproduced not only on passing the said signal indicator but also at acertain distance before reaching the same.

Nevertheless, when it is desired to carry the said combination intopractice, it will be preferable to slightly modify the constitution ofthe circuit of the coils A and B since otherwise a certain confusionmight result between the signal line blocked and the signal given by thepresence of another vehicle on the track, due to the impedance of thetrack circuit then being of a nature similar to that of the simplecircuit formed by the coils A and B in series.

To this end, there may then be used, for example, the arrangementaccording to Figure 5. The coils S and F are coupled, on passing a tracksignal indicator, with the coils A and B as in Figures 1 and 2. Inaddition however, they are also strongly coupled with the trackindicated at V, which may be short circuited in front of the vehicle byanother vehicle or at M by a mechanism controlled by another signalindicator or from a signal box. There is connected in series with eachof the coils A and B a resistance W1 and a capacity K1 of suitablevalues. The capacity will be chosen in such manner that the unit formedby the self-induction of the coil and the capacity K1 in seriestherewith is approximately tuned to the frequency of the currentsupplied by the generator G. The resistance W1 serves effectively todamp the system so as to avoid the possible influence of variations offrequency of G. It will readily be understood that in this case, when noimpedance Z is connected in the circuit, the electromotive force inducedby B in the coil F is in quadrature with that produced by the trackcurrent and the two signals closed line and train ahead cannot thereforebe confused. This arrangement will be chosen for the repetition of thesignal line blocked.

By giving a suitable value to Z (capacitative or self-inductancereactance according to the relative sense of the couplings of S and Fwith the track circuit and with the coils A and B) there may be produceda signal opposite in phase to that which is given by the current in thetrack circuit. Finally, by using in a similar manner to that of Figure2, a second coil A1 of opposite winding to A, there may be obtained asignal in phase opposition to that which corresponds to the blockedtrack (Figure 5). A1, like A, will be connected in series with acapacity K1 and a resistance W1, and the impedance Z1 introduced by thecontact controlled by the track signal indicator will be a resistance ofsmall value.

As it is desirable, at least for the most important indications such asline closed and warning, that. the signal indication on the vehicleshould not disappear as soon as the corresponding track signal indicatorhas been passed, it will be of advantage to use for one at least of therelays R1 and R2 a relay of the type known as guarded. This term isgiven to a relay which after having been deenergized cannot becomeenergized again by itself. To efiect this, it is sufficient, forexample, for the de-energization to close a contact short-circuiting thecoil of the relay.

Let it be supposed, for example, that the following code has beenadopted:

1.-Line blocked: R1 and. R2 de-energized.

2,"Warning: R1 de-energized, R2 energized.

3.Line clear: R1 and R2 energized.

4.--Track current (vehicle in front) R1 energized, R2 de-energized.

It will then be of advantage to adopt the arrangement that R1 is aguarded relay and is provided furthermore with a system of contacts suchthat when R1 and R2 are simultaneously de-energized, R2 also cannotenergize itself again. When R1 is energized, R2 will not be guarded. Thefourth indication given by the track current is in fact of a continuouscharacter and is not transitory like that which is produced on passing atrack signal indicator.

With reference once more, to Figure 6, it will be understood that thisfigure shows an arrangement according to the above explanation. Thearmature l of the relay R1 short-circuits the coil of this latter whenit is de-energized. The armature 2 is in series with the armature 4 ofthe relay R2. These two armatures close a circuit short circuiting thecoil of R2 when the two relays are de-energized. The arrangement canonly be set in operation again when the cause of the deenergization ofthe relays disappears and the contacts I, 2, and 4 are opened, forexample by hand by means of a push button, not shown.

The principle of the system of the repetition of signals which has justbeen described may of course be extended to a number of signals greaterthan four. The vector OE: could, for example, be given six positionsseparated by sixty degrees,

by utilizing three relays or any other similar arrangement. It willtherefore be understood that the invention is in no way limited to theparticular arrangements above described but comprises all modificationsthereof within the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United Statesis:-

1. A signaling system for railway and like installations in which avehicle travels along a predetermined track, comprising a firstelectrical system carried by said vehicle including an alternatingcurrent generator, an emitter coil in the circuit of said generator, areceiver coil located so as to avoid inductive coupling with saidemitter coil and a receiver connected to be supplied differentially bysaid generator and by said receiver coil and comprising means formeasuring the difference of phase between the electromotive force insaid receiver coil and said generator current, and a stationaryelectrical system located alongside said track and comprising twoinductances forming a closed circuit and means for controllablyconnecting a common impedance in shunt across each of said inductances,said inductances of said stationary system becoming coupled respectivelywith said emitter and receiver coils of said system carried by saidvehicle when said vehicle passes along said track so that anelectromotive force is induced in said inductances by said emitter coil,which electromotive force in turn induces an electromotive force in saidreceiver coil of said first mentioned system which is supplied to saidreceiver.

2. A signaling system for railway and like installations in which avehicle travels along a predetermined track, comprising a firstelectrical system carried by said vehicle including a generator ofalternating current of audio frequency,

an emitter coil in the circuit of said generator,

a receiver coil located so as to avoid inductive coupling Withsaidemitter coil, and a receiver connected to be supplied difierentially bysaid generator and by said receiver coil and comprising means formeasuring the difi'erence of phase between the electromotive force insaid receiver coil and said generator current and means responsive to anaudio frequency current for giving an indication in accordance with saidphasedifference, and a stationary electrical system located alongsidesaid track and comprising two inductances forming a closed circuit andmeans for controllably connecting a common impedance in shunt acrosseach of said inductances, said inductances of said stationary systembecoming coupled respectively with said emitter and receiver coils ofsaid system carried by said vehicle when said vehicle passes along saidtrack, so that an electromotive force is induced in said inductances bysaid emitter coil, which electromotive force in turn induces anelectromotive force in said receiver coil of said first mentioned systemwhich is supplied to said receiver.

3. In a signaling system for railway and like installations in which avehicle travels along a predetermined track and a signal indication isgiven by induction between an electrical system carried on saidtravelling vehicle and a stationary electrical system located alongsidesaid track, said stationary electrical system located alongside saidtrack comprising two inductances forming a closed circuit and means forcontrollably short circuiting each of said inductances by an impedance.

4. In a signaling system for railway and like installations in which avehicle travels along a predetermined track and a signal indication isgiven by induction between an electrical system carried on saidtravelling vehicle and a stationary electrical system located alongsidesaid track, said stationary electrical system located alongside saidtrack comprising two inductances in series, means for short circuitingeach of said inductances by a common impedance and means foradditionally inserting in the circuit instead of one of said inductancesa further inductance wound oppositely to the said last inductance.

5. In a signaling system for railway and like installations in which avehicle travels along a predetermined track and a signal indication isgiven by induction between an electrical system carried on saidtravelling vehicle and a stationary electrical system located alongsidesaid track, said stationary electrical system located alongside saidtrack comprising at least two inductances in series, means for shortcircuiting each of said inductances by a common impedance, and aresistance and a capacity connected in series with each of saidinductances.

6. A signaling system for railway and like installations in which avehicle travels along a predetermined track provided with a track signalindicator, comprising a first electrical system carried by said vehicleincluding an alternating current generator, an emitter coil in thecircuit of said generator, a receiver coil located so as to avoidinductive coupling with said emitter coil, and a receiver connected tobe supplied differentially by said generator and by said receiver coiland comprising means for measuring the difierence of phase between theelectromotive force in said receiver coil and said generator current,and a stationary electrical system located alongside said track andcomprising at least two inductances in series and means controlled bysaid track signal indicator for short circuiting each of saidinductances by a common impedance and for additionally inserting in thecircuit instead of one of said inductances a further inductance woundoppositely to the said last inductance, said inductances of saidstationary system becoming coupled respectively with said emitter andreceiver coils of said system carried by said vehicle when said vehiclepasses along said track, so that an electromotive force is induced insaid inductances by said emitter coil, which electromotive force in turninduces an electromotive force in said receiver coil of said firstmentioned system which is supplied to said receiver.

installations in which a vehicle travels along a' predetermined trackprovided with electrically insulating sleepers, comprising a firstelectrical system carried by said vehicle including an alternatingcurrent generator, an emitter coil in the circuit of said generator, areceiver coil located so as to avoid inductive coupling with saidemitter coil and a receiver connected to be supplied differentially bysaid generator and by said receiver coil and comprising means formeasuring and indicating the difierence of phase between theelectromotive force in said receiver coil and said generator current,and a stationary electrical system located alongside said track andcomprising two inductances and means for controllably connecting animpedance in circuit with said inductances, said inductances of saidstationary system becoming coupled respectively with said emitter andreceiver coils of said system carried by said vehicle when said vehiclepasses along said track, so that an electromotive force is induced insaid inductances by said emitter coil which electromotive force in turninduces an electromotive force in said receiver coil of said firstmentioned system which is supplied to said receiver, and means foradditionally controlling the indications given by said receiver inaccordance with the condition of a track section ahead of the tracksection on which said vehicle cooperates with said stationary systemalongside said track.

3. A signaling system for railway and like installations in which avehicle travels along a predetermined track provided with electricallyinsulating sleepers comprising a first electrical system carried by saidvehicle including an alternating current generator, an emitter coil inthe circuit of said generator, a receiver coil located so as to avoidinductive coupling with said emitter coil and a receiver connected to besupplied differentially by said generator and by said receiver coil andcomprising means for measuring and indicating the difference ofphasebetween the electromotive force in said receiver coil and saidgenerator current'and means for coupling said coils with said rails sothat said receiver also indicates a short circuit of the track sectionin front'of the track section occupied by said vehicle, and a stationaryelectrical system located alongside said track and comprising at leasttwo inductances in series, a resistance and a capacity in series witheach of said inductances, and means for controllably short circuitingeach of said inductances by a common impedance, said inductances of saidstationary system becoming coupled respectively with said emitter andreceiver coils of said system carried by said vehicle when said vehiclepasses along said track, so that an electromotive force is induced insaid inductances by said emitter coil, which electromotive force in turninduces an electromotive force in said receiver coil of said firstmentioned system whioh is supplied to said receiver.

9. In a signaling system for railway and like installations in which avehicle travels along a predetermined track and a signal indicationisgiven by induction between an electrical system carried by saidtravelling vehicle and a stationary electrical system located alongsidesaid track, an apparatus on said vehicle comprising an alternatingcurrent generator, an emitter coil in the circuit of said generator, areceiver coil located so as -to avoid inductive coupling with saidemitter coil, an impedance energized by said generator and comprising aseries of partial im pedances, the voltages at each of said partialimpedances presenting between themselves and with respect to saidgenerator current predetermined phase displacements, a transformersupplied by each of said voltages and having a corresponding number ofsecondary windings, the extremities of each of said windings of saidtransformer being connected to a circuit composed of two seriesconnected units each comprising a resistance shunted by a capacity, aconnection from the mid point of each of said secondary windings to thejunction of the corresponding resistance capacity units, means forintroducing into each of said connections a voltage furnished by saidreceiver coil, and signal indicating means connected to said resistancecapacity-unit circuits.

10. In a signaling system for railway and like installations in whichavehicle travels along a predetermined track and a signal indication isgiven by induction between an electrical system carried by Saidtravelling vehicle and a stationary electrical system located alongsidesaid track, an apparatus on said vehicle comprising an alternatingcurrent generator, an emitter coil in the circuit of said generator, areceiver coil located so as to avoid inductive coupling with saidemitter coil, an impedance energized by said generator and comprising aseries of partial impedances, the voltages at each of said partialimpedances presenting between themselves and with respect to saidgenerator current predetermined phase displacements, a transformersupplied by each of said voltages and having a corresponding number ofsecondary windings, the extremities of each of said secondary windingsof said transformer being connected to a circuit composed of two seriesconnected units each comprising a resistance shunted by a capacity, aconnection from the mid point of each of said secondary windings to thejunction of the corresponding resistance capacity units, means forintroducing into each of said connections a voltage iurnished by saidreceiver coil, means for collecting at the output of said receiver anumber of voltages representing a predetermined signal, electromagneticrelays controlled in accordance with said voltages, and a circuitcomprising a plurality of signal indicators and the contacts on saidelectromagnetic relays so connected as to render each of said signalindicators operative for a different predetermined combination ofenergization of said electromagnetic relays. 1

11. A signaling system for railway and like installations in which avehicle travels along a predetermined track provided with a track signalindicator, comprising a first electrical system 'located alongside saidtrack and comprising two inductances and means controlled by said tracksignal indicator for connecting an impedance in circuit with saidinductance, and a second electrical system carried by said vehicleincluding a generator of alternating current of audio frequency, anemitter coil in the circuit of said generator and a receiver coillocated so as to avoid inductive coupling with said emitter coil, sothat said inductance of said stationary system alongside said trackbecomes coupled respectively with said emitter and receiver coils ofsaid system carried by said vehicle when said'vehicle passes along saidtrack, whereby an electromotive force is induced in said inductances bysaid emitter coil, which electromotive force in turn induces anelectromotive force in said receiver coil of said first mentioned systemwhich is supplied to said receiver, a receiver supplied difierentiallyby said generator and by said receiver coil and comprising means formeasuring the diiTerence of phase between the electromotive force insaid receiver coil and said generator current and means responsive to anaudio frequency current for giving an indication in accordance with saidphase difference, said two last mentioned means comprising an impedanceenergized by said generator and comprising a series of partialimpedances, the voltages at each of said partial impedances presentingbetween themselves and with respect to said generator currentpredetermined phase displacements, a transformer supplied by each ofsaid voltages and having a corresponding number of secondary windings,the extremities of each of said secondary windings of said transformerbeing connected to a circuit composed of two series connected units eachcomprising a resistance shunted by a capacity, a connection from the midpoint of each of said secondary windings to the junction of thecorresponding resistance capacity units, means for introducing into eachof said connections a potential drop furnished by said receiver coil,means for collecting at the output of said receiver a number of voltagesrepresenting a predetermined signal, grid controlled valve relayssupplied respectively by said voltages, electromagnetic relayscontrolled by said ionized gas valve relays and a circuit comprising aplurality of signal indicators and the contacts of said electromagneticrelays so connected as to render each of said signal inv dicatorsoperative for a difierent predetermined combination of energization ofsaid electromagnetic relays.

PAUL NICOLAS.

